PERSISTENT DIRECTION-CHANGING POSITIONAL NYSTAGMUS - ANOTHER VARIANT OF BENIGN POSITIONAL NYSTAGMUS

Positional nystagmus that does not fatigue, persists as long as the po sition is held, and changes direction in different head positions has typically been attributed to central vestibular lesions. We recently s tudied three patients who presented with positional nystagmus having t hese features but almost certainly of benign peripheral origin. All th ree had an initial history typical of benign positional vertigo and, i n two, the persistent direction-changing positional nystagmus occurred after the patient underwent a maneuver to remove debris from the post erior semicircular canal. The positional nystagmus profile and clinica l course are consistent with the debris leaving the posterior semicirc ular canal and becoming attached to the cupula of the horizontal semic ircular canal.